ExplanationThe conclusion is that the Japanese attack on Pearl Harbor caused the U.S. to enter World War II. The premises establish that before Pearl Harbor, the U.S. was neutral, but after the attack, the U.S. entered the war.
To weaken this cause-effect argument, we should show that:
1. There were other causes that made entering the war inevitable.
2. The U.S. was already acting like a participant before Pearl Harbor, so the attack wasn't truly the decisive cause.
3. The U.S. would have entered the war in the near future regardless.
Option B says the U.S. had been engaging in secret military operations against Germany and Japan before Pearl Harbor. If true, then the U.S. was already effectively at war (or about to be), so Pearl Harbor didn't cause entry, entry was already happening due to prior actions. This most directly attacks the
"cause" claim.
Option A and
C are supportive acts short of war, which actually make it less surprising that Pearl Harbor led to war, so such facts don't seriously weaken.
Option D is neutral or even supports that the U.S. was avoiding war, so doesn’t weaken.
Option E is a vague generalization, not a concrete fact about pre-Pearl Harbor military involvement that changes causation.
Answer: B